1. Field of the Invention
The present invention pertains generally to navigation systems, and particularly to a navigation system that navigates a vehicle along a preselected route while giving a user a display of maps and visual and/or audible instructions, and a computer-readable information recorded medium in which a navigation control program for implementing the above navigation process is recorded.
2. Description of Related Art
In-vehicle navigation systems are widely used in recent years to navigate a vehicle, while displaying maps on a display such as a liquid-crystal display panel mounted in the vehicle.
Many navigation systems provide for routing by preselecting an appropriate route to a scheduled destination based on the time required to reach such destination, etc., and displaying the preselected route on the display at the time of departure to guide a user along the preselected route henceforward.
In such navigation systems, however, the route preselection is usually carried out only at the time of departure, with the sole exception that the preselected route is revised, when the vehicle is driving off such preselected route during travel, to reselect a new route to the scheduled destination from the current vehicle""s position which is off the preselected route.
Thus, if the user is involved in traffic congestion, or encounters suspension of traffic, for example, along the preselected route, the navigation systems, due to having to cope with such contingencies along the preselected route, may not be able to provide appropriate instructions to the user, hence causing problems that he cannot arrive at the destination on schedule, for example.
The present invention has been made in view of the above problems, and an object thereof is, therefore, to provide a navigation system that can navigate a vehicle to a destination efficiently, even when the vehicle, for example, encounters unexpected situations along a route selected at the time of its departure, by appropriately optimizing the route to the destination on the way, and a computer-readable information recorded medium in which a navigation control program for implementing the above navigation process is recorded.
The above object of the present invention can be achieved by a navigation system of the present invention. The system is provided with: a route selecting device for selecting a scheduled route along which a mobile body is scheduled to move; a searching device for searching for a different route while said mobile body is moving along said scheduled route, said different route serving to reach a destination for which said mobile body moves along said scheduled route; a comparing device for comparing said searched different route with said scheduled route for movement of said mobile body from a current position of said mobile body onward; and a notifying device for notifying a comparison result obtained by said comparing device.
According to the present invention, a new route which is different from the scheduled route is searched during moving, and notice is given of the result of a comparison between the different route that is searched and the scheduled route, whereby the user can be informed of the best route available at that point of time during moving.
In one aspect of the present invention, a reselecting device for reselecting one of said scheduled route and said different route as a new scheduled route for said movement of said mobile body from said current position onward, based on notice given by said notifying device.
According to this aspect, the user can reselect the best route available for moving from the current position onward based on the given notice, for use as a new scheduled route.
In another aspect of the present invention, an acquiring device for acquiring traffic congestion information about traffic congestion along said scheduled route, from an external source, wherein said searching device starts searching for said different route upon acquisition of a new piece of said traffic congestion information.
According to this aspect, a search for a different route CL starts upon acquisition of a new piece of traffic congestion information, whereby the user can search for another different route based on the latest traffic congestion information.
In further aspect of the present invention, the system is further provided with a time measuring device for measuring time, wherein said searching device starts searching for said different route every time a preset time elapses.
According to this aspect, a search for a different route starts every time a preset time elapses, whereby the user can search for the best different route periodically.
In further aspect of the present invention, said notifying device gives notice of a time which is required to reach said destination if said mobile body moves along said different route.
According to this aspect, the user can recognize the shortest route to the destination.
In further aspect of the present invention, the system is further provided with a detecting device for detecting a diverging point at which said scheduled route and said different route diverge, wherein said notifying device gives notice of said comparison result upon arrival of said mobile body at a point which is away from said diverging point by a preset distance.
According to this aspect, notice is given of the different route upon arrival of the mobile unit at a point which is away from the diverging point by a preset distance, whereby the user can recognize the comparison result before the scheduled route and the different route diverge.
In further aspect of the present invention, said notifying device gives notice of said comparison result only upon determination, based on said comparison result, that said different route can bring said mobile unit to said destination earlier than said scheduled route if said mobile body moves along said different route.
According to this aspect, the user can recognize only such a comparison result as being useful for his travel to the destination.
In further aspect of the present invention, said notifying device gives said notice at least visually or audibly.
According to this aspect, the user can recognize the comparison result in a simple and easy way.
The above object of the present invention can be achieved by an information recorded medium of the present invention wherein a navigation control program is recorded so as to be read by a computer, said computer included in a navigation system for navigating a mobile body. The navigation control program causes said computer to function as: a selecting device for selecting a scheduled route along which a mobile body is scheduled to move; a searching device for searching for a different route while said mobile body is moving along said scheduled route, said different route serving to reach a destination for which said mobile body moves along said scheduled route; a comparing device for comparing said searched different route with said scheduled route for movement of said mobile body from a current position of said mobile body onward; and a notifying device for notifying a comparison result obtained by said comparing device.
According to the present invention, the computer is caused to function to search a new route which is different from the scheduled route during moving, and give notice of the result of a comparison between the different route that is searched and the scheduled route, whereby the user can be informed of the best route available at that point of time during moving.
In one aspect of the present invention, said navigation control program further causes said computer to as a reselecting device for reselecting one of said scheduled route and said different route as a new scheduled route for said movement of said mobile body from said current position onward, based on notice given by said notifying device.
According to this aspect, the user can reselect the best route available for moving from the current position onward based on the given notice, for use as a new scheduled route.
In another aspect of the present invention, said navigation control program further causes said computer to function as an acquiring device for acquiring traffic congestion information about traffic congestion along said scheduled route, from an external source, and said searching device starts searching for said different route upon acquisition of a new piece of said traffic congestion information.
According to this aspect, the computer is caused to function to start a search for a different route upon acquisition of a new piece of traffic congestion information, whereby the user can search for another different route based on the latest traffic congestion information.
In further aspect of the present invention, said navigation control program further causes said computer to function as a time measuring device for measuring time, and said searching device starts searching for said different route every time a preset time elapses.
According to this aspect, the computer is caused to function to start a search for a different route every time a preset time elapses, whereby the user can search for the best different route periodically.
In further aspect of the present invention, said notifying device gives notice of a time which is required to reach said destination if said mobile body moves along said different route.
According to this aspect, the user can recognize the shortest route to the destination.
In further aspect of the present invention, said navigation control program further causes said computer to function as a detecting device for detecting a diverging point at which said scheduled route and said different route diverge, and said notifying device gives notice of said comparison result upon arrival of said mobile body at a point which is away from said diverging point by a preset distance.
According to this aspect, the computer is caused to function to give notice of the different route upon arrival of the mobile unit at a point which is away from the diverging point by a preset distance, whereby the user can recognize the comparison result before the scheduled route and the different route diverge.
In further aspect of the present invention, said notifying device gives notice of said comparison result only upon determination, based on said comparison result, that said different route can bring said mobile body to said destination earlier than said scheduled route if said mobile body moves along said different route.
According to this aspect, the user can recognize only such a comparison result as being useful for his travel to the destination.